Photoelectric conversion element, optical sensor, imaging element, and compound

ABSTRACT

The invention provides a photoelectric conversion element including a photoelectric conversion film excellent in vapor deposition suitability and exhibiting excellent photoelectric conversion efficiency in a case where the photoelectric conversion film is a thin film, an optical sensor, an imaging element, and a compound. The photoelectric conversion element of the embodiment of the invention includes a conductive film, a photoelectric conversion film, and a transparent conductive film, in this order, in which the photoelectric conversion film contains a compound represented by Formula (1).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2018/025078 filed on Jul. 2, 2018, which claims priority under 35U.S.C. § 119(a) to Japanese Patent Application No. 2017-133896 filed onJul. 7, 2017. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a photoelectric conversion element, anoptical sensor, an imaging element, and a compound.

2. Description of the Related Art

In the related art, a planar solid-state imaging element in whichphotodiodes (PDs) are two-dimensionally arranged and a signal chargegenerated in each PD is read out by a circuit is widely used as asolid-state imaging element.

In order to realize a color solid-state imaging element, a structure inwhich a color filter transmitting light of a specific wavelength isdisposed on a light incident surface side of the planar solid-stateimaging element is generally used. Currently, a single plate solid-stateimaging element in which the color filter transmitting blue (B) light,green (G) light, and red (R) light is regularly arranged on each PDwhich is two-dimensionally arranged is well known. However, in thissingle plate solid-state imaging element, light which is not transmittedthrough the color filter is not used, thus light utilization efficiencyis poor.

In order to solve these disadvantages, in recent years, development of aphotoelectric conversion element having a structure in which an organicphotoelectric conversion film is disposed on a substrate for reading outa signal has progressed.

US2014/0097416A discloses, for example, a photoelectric conversionelement having a photoelectric conversion film containing the followingcompounds.

JP2005-209359A discloses a semiconductor for a photoelectric conversionmaterial containing the following pigment.

JP2005-129430A discloses a semiconductor for a photoelectric conversionmaterial containing the following heterocyclic compound.

SUMMARY OF THE INVENTION

In recent years, further improvements are also required for variouscharacteristics required for a photoelectric conversion element used inan imaging element and an optical sensor, along with demands forimproving performance of the imaging element, the optical sensor, andthe like.

For example, regarding the photoelectric conversion element, it isrequired that good photoelectric conversion efficiency can be maintainedeven in a case where thinning of the photoelectric conversion film isadvanced (for example, in a case where the photoelectric conversion filmis made to be 100 nm).

The inventors of the invention have produced a photoelectric conversionelement using a compound (for example, the above-described compound)disclosed in US2014/0097416A, and have examined the photoelectricconversion efficiency in a case where the photoelectric conversion filmis a thin film (hereinafter, referred to as the “photoelectricconversion efficiency in a case of a thin film”). As a result, theinventors have found that the characteristics do not necessarily reachthe level required recently and further improvement is necessary.

Furthermore, the inventors of the invention have examined JP2005-209359Aand JP2005-129430A and found that it is difficult to produce aphotoelectric conversion film using a vapor deposition method dependingon the structure of the compounds disclosed in JP2005-209359A andJP2005-129430A. Hereinafter, the suitability for producing thephotoelectric conversion film when using the vapor deposition method isalso referred to as “vapor deposition suitability”.

In view of the above-described circumstances, an object of the inventionis to provide a photoelectric conversion element including aphotoelectric conversion film excellent in the vapor depositionsuitability, and excellent photoelectric conversion efficiency even in acase where the photoelectric conversion film is a thin film.

Another object of the invention is to provide an optical sensor and animaging element including the photoelectric conversion element. Stillanother object of the invention is to provide a compound applied to thephotoelectric conversion element.

The inventors of the invention have conducted extensive studies on theabove-described problems. As a result, the inventors have found that itis possible to solve the above-described problems by applying thecompound having a predetermined structure to the photoelectricconversion film, and have completed the invention.

(1) A photoelectric conversion element comprising a conductive film, aphotoelectric conversion film, and a transparent conductive film, inthis order, in which the photoelectric conversion film contains acompound represented by Formula (1) described below.

(2) The photoelectric conversion element according to (1), in which thecompound represented by Formula (1) described below is a compoundrepresented by Formula (2) described below.

(3) The photoelectric conversion element according to (2), in which inFormula (2) described below, R^(b1) represents an alkyl group, an arylgroup, a heteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a—CO-heteroaryl group, which may have a substituent.

(4) The photoelectric conversion element according to (2) or (3), inwhich in Formula (2) described below, X¹ represents an oxygen atom, asulfur atom, —NR^(b6)—, or —CR^(b11)═CR^(b12)—.

(5) The photoelectric conversion element according to any one of (2) to(4), in which in Formula (2) described below, X¹ represents an oxygenatom or a sulfur atom.

(6) The photoelectric conversion element according to any one of (1) to(5), in which the compound represented by Formula (1) described below isa compound represented by Formula (3) described below.

(7) The photoelectric conversion element according to (6), in which inFormula (3) described below, R^(c3) represents an aryl group or aheteroaryl group, which may have a substituent.

(8) The photoelectric conversion element according to any one of (1) to(7), in which the photoelectric conversion film further contains ann-type organic semiconductor and has a bulk hetero structure formed in astate where the compound represented by Formula (1) described below andthe n-type organic semiconductor are mixed.

(9) The photoelectric conversion element according to any one of (1) to(8), further comprising one or more interlayers between the conductivefilm and the transparent conductive film, in addition to thephotoelectric conversion film.

(10) An optical sensor comprising the photoelectric conversion elementaccording to any one of (1) to (9).

(11) An imaging element comprising the photoelectric conversion elementaccording to any one of (1) to (9).

(12) A compound represented by Formula (2) described below.

According to the invention, it is possible to provide a photoelectricconversion element including a photoelectric conversion film excellentin the vapor deposition suitability, and excellent photoelectricconversion efficiency even in a case where the photoelectric conversionfilm is a thin film.

According to the invention, it is possible to provide an optical sensorand an imaging element including the photoelectric conversion element.According to the invention, it is possible to provide a compound appliedto the photoelectric conversion element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional view showing an example of aconfiguration of a photoelectric conversion element.

FIG. 1B is a schematic cross-sectional view showing an example of aconfiguration of a photoelectric conversion element.

FIG. 2 is a schematic cross-sectional view of one pixel of a hybrid typephotoelectric conversion element.

FIG. 3 is a schematic cross-sectional view of one pixel of an imagingelement.

FIG. 4 is a ¹H nuclear magnetic resonance (NMR) chart of a compound(D-1).

FIG. 5 is a ¹H nuclear magnetic resonance (NMR) chart of a compound(D-3).

FIG. 6 is a ¹H nuclear magnetic resonance (NMR) chart of a compound(D-4).

FIG. 7 is a ¹H nuclear magnetic resonance (NMR) chart of a compound(D-6).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of a photoelectric conversion elementof the invention will be described.

In the present specification, a substituent for which whether it issubstituted or unsubstituted is not specified may be further substitutedwith a substituent (for example, a substituent W described below) withinthe scope not impairing an intended effect. For example, the expressionof “alkyl group” refers to an alkyl group with which a substituent (forexample, a substituent W described below) may be substituted.

In addition, in the present specification, the numerical rangerepresented by “to” means a range including numerical values denotedbefore and after “to” as a lower limit value and an upper limit value.

The bonding direction of a divalent group represented in the presentspecification is not particularly limited, for example, when X¹ inFormula (2) described below is —N═CR^(b13), in a case where a positionbonded to the R^(b3) side is *1, a position bonded to the pyrrole ringgroup side is *2, X¹ may be *1-N═CR^(b13)—*2 or *1-CR^(b13)═N—*2.

[Photoelectric Conversion Element]

A feature of the invention compared to the related art is that acompound represented by Formula (1) described below (hereinafter alsoreferred to as a “specific compound”) is used for a photoelectricconversion film.

The inventors of the invention have thought that in the specificcompound, linking of a site acting as an acceptor having a ringrepresented by A of Formula (1) described below and a site acting as adonor having a pyrrole ring group contributes to the excellentphotoelectric conversion efficiency in a case of a thin film.

The inventors of the invention have found that the presence of apredetermined acidic group and a salt thereof tends to have a badinfluence on the vapor deposition suitability of the compound. Morespecifically, the inventors have found that in a case where the specificcompound does not have any of a carboxy group, a salt of a carboxygroup, a phosphoric acid group, a salt of a phosphoric acid group, asulfonic acid group, or a salt of a sulfonic acid group, the excellentvapor deposition suitability can be maintained in addition to theexcellent photoelectric conversion efficiency in a case of the thinfilm.

In the present specification, a “salt” means any one of an alkali metalsalt, an alkali earth metal salt, an ammonium salt, or a substitutedammonium salt.

Hereinafter, preferred embodiments of a photoelectric conversion elementof the invention will be described with reference to the drawings. FIGS.1A and 1B show schematic cross-sectional views of one embodiment of aphotoelectric conversion element of the invention.

A photoelectric conversion element 10 a shown in FIG. 1A has aconfiguration in which a conductive film (hereinafter, also referred toas a lower electrode) 11 functioning as the lower electrode, an electronblocking film 16A, a photoelectric conversion film 12 containing thespecific compound described below, and a transparent conductive film(hereinafter, also referred to as an upper electrode) 15 functioning asthe upper electrode are laminated in this order.

FIG. 1B shows a configuration example of another photoelectricconversion element. A photoelectric conversion element 10 b shown inFIG. 1B has a configuration in which the electron blocking film 16A, thephotoelectric conversion film 12, a positive hole blocking film 16B, andthe upper electrode 15 are laminated on the lower electrode 11 in thisorder. The lamination order of the electron blocking film 16A, thephotoelectric conversion film 12, and the positive hole blocking film16B in FIGS. 1A and 1B may be appropriately changed according to theapplication and the characteristics.

In the photoelectric conversion element 10 a (or 10 b), it is preferablethat light is incident on the photoelectric conversion film 12 throughthe upper electrode 15.

In a case where the photoelectric conversion element 10 a (or 10 b) isused, the voltage can be applied. In this case, it is preferable thatthe lower electrode 11 and the upper electrode 15 form a pair ofelectrodes and the voltage of 1×10⁻⁵ to 1×10⁷ V/cm is applied thereto.From the viewpoint of performance and power consumption, the voltage tobe applied is more preferably 1×10⁴ to 1×10⁷ V/cm, and still morepreferably 1×10⁻³ to 5×10⁶ V/cm.

The voltage application method is preferable that the voltage is appliedsuch that the electron blocking film 16A side is a cathode and thephotoelectric conversion film 12 side is an anode, in FIGS. 1A and 1B.In a case where the photoelectric conversion element 10 a (or 10 b) isused as an optical sensor, or also in a case where the photoelectricconversion element 10 a (or 10 b) is incorporated in an imaging element,the voltage can be applied by the same method.

As described in detail below, the photoelectric conversion element 10 a(or 10 b) can be suitably applied to applications of the optical sensorand the imaging element.

In addition, a schematic cross-sectional view of another embodiment of aphotoelectric conversion element of the invention is shown in FIG. 2.

The photoelectric conversion element 200 shown in FIG. 2 is a hybridtype photoelectric conversion element comprising an organicphotoelectric conversion film 209 and an inorganic photoelectricconversion film 201. The organic photoelectric conversion film 209contains the specific compound described below.

The inorganic photoelectric conversion film 201 has an n-type well 202,a p-type well 203, and an n-type well 204 on a p-type silicon substrate205.

Blue light is photoelectrically converted (a B pixel) at a p-n junctionformed between the p-type well 203 and the n-type well 204, and redlight is photoelectrically converted (an R pixel) at a p-n junctionformed between the p-type well 203 and the n-type well 202. Theconduction types of the n-type well 202, the p-type well 203, and then-type well 204 are not limited thereto.

Furthermore, a transparent insulating layer 207 is disposed on theinorganic photoelectric conversion film 201.

A transparent pixel electrode 208 divided for each pixel is disposed onthe insulating layer 207. The organic photoelectric conversion film 209which absorbs green light and performs photoelectric conversion isdisposed on the transparent pixel electrode in a single layerconfiguration commonly for each pixel. The electron blocking film 212 isdisposed on the organic photoelectric conversion film in a single layerconfiguration commonly for each pixel. A transparent common electrode210 with a single layer configuration is disposed on the electronblocking film. A transparent protective film 211 is disposed on theuppermost layer. The lamination order of the electron blocking film 212and the organic photoelectric conversion film 209 may be reversed fromthat in FIG. 2, and the common electrode 210 may be disposed so as to bedivided for each pixel.

The organic photoelectric conversion film 209 constitutes a G pixel fordetecting green light.

The pixel electrode 208 is the same as the lower electrode 11 of thephotoelectric conversion element 10 a shown in FIG. 1A. The commonelectrode 210 is the same as the upper electrode 15 of the photoelectricconversion element 10 a shown in FIG. 1A.

In a case where light from a subject is incident on the photoelectricconversion element 200, green light in the incident light is absorbed bythe organic photoelectric conversion film 209 to generate opticalcharges. The optical charges flow into and accumulate in a green signalcharge accumulation region not shown in the drawing from the pixelelectrode 208.

Mixed light of the blue light and the red light transmitted through theorganic photoelectric conversion film 209 enters the inorganicphotoelectric conversion film 201. The blue light having a shortwavelength is photoelectrically converted mainly at a shallow portion(in the vicinity of the p-n junction formed between the p-type well 203and the n-type well 204) of a semiconductor substrate (the inorganicphotoelectric conversion film) 201 to generate optical charges, and asignal is output to the outside. The red light having a long wavelengthis photoelectrically converted mainly at a deep portion (in the vicinityof the p-n junction formed between the p-type well 203 and the n-typewell 202) of the semiconductor substrate (the inorganic photoelectricconversion film) 201 to generate optical charges, and a signal is outputto the outside.

In a case where the photoelectric conversion element 200 is used in theimaging element, a signal readout circuit (an electric charge transferpath in a case of a charge coupled device (CCD) type, or ametal-oxide-semiconductor (MOS) transistor circuit in a case of acomplementary metal oxide semiconductor (CMOS) type), or the greensignal charge accumulation region is formed in a surface portion of thep-type silicon substrate 205. In addition, the pixel electrode 208 isconnected to the corresponding green signal charge accumulation regionthrough vertical wiring.

Hereinafter, the form of each layer constituting the photoelectricconversion element of the embodiment of the invention will be describedin detail.

[Photoelectric Conversion Film]

<Specific Compound>

The photoelectric conversion film 12 (or the organic photoelectricconversion film 209) is a film containing the specific compound as aphotoelectric conversion material. The photoelectric conversion elementhaving the photoelectric conversion film excellent in the vapordeposition suitability and exhibiting the excellent photoelectricconversion efficiency in a case of a thin film can be obtained by usingthe compound.

Hereinafter, the specific compound will be described in detail.

The suitable conditions of the specific compound mentioned below arementioned from the point which the photoelectric conversion efficiencyin a case of a thin film is more excellent unless otherwise noted.

Also, unless otherwise noted, it is preferable that the substituentsthat may be included in the specific compound are each independently anyone of the substituents W described below.

In the present specification, Formula (1) includes all geometric isomersthat can be distinguished based on the C═C double bond constituted by acarbon atom to which R^(a7) bonds and a carbon atom adjacent thereto inFormula (1). That is, both the cis isomer and the trans isomer which aredistinguished based on the C═C double bond are included in the compoundrepresented by Formula (1).

The same applies to geometric isomers that can be distinguished based onthe C═C double bond constituted by a carbon atom to which R^(b5) bondsand a carbon atom adjacent thereto in Formula (2) described below.

In Formula (1), m represents an integer of 0 or more. Among these, m ispreferably 0 to 4, more preferably 1 to 3, and still more preferably 1.

R^(a1) to R^(a7) each independently represent a hydrogen atom or asubstituent. The type of the substituent is not particularly limited,but a group exemplified by a substituent W described below is mentioned.

R^(a1) to R^(a7) may be linked to each other to form a ring.

For example, R^(a1) and R^(a2) may be linked to each other to form aring, R^(a1) and R^(a7) may be linked to each other to form a ring,R^(a2) and R^(a3) may be linked to each other to form a ring, R^(a3) andR^(a4) may be linked to each other to form a ring, R^(a4) and R^(a5) maybe linked to each other to form a ring, R^(a5) and R^(a6) may be linkedto each other to form a ring, and R^(a3) and R^(a5) may be linked toeach other to form a ring. In a case where R^(a3) and R^(a5) are linkedto each other to form a ring, m is preferably 0. In a case where aplurality of R^(a2)s are present, the plurality of R^(a2)s may be linkedto each other to form a ring.

In a case where a plurality of R^(a4)s are present, the plurality ofR^(a4)s may be linked to each other to form a ring.

Among these, it is preferable that V, which is present closest to R^(a5)among the plurality of R^(a4)s, and R^(a5) are linked to each other toform a ring. In other words, it is preferable that a ring formed bybonding R^(a4) and R^(a5) to each other above is condensed with apyrrole ring group specified in Formula (1) to form a condensed ringstructure (a fused ring structure).

Also, the group formed by bonding R^(a4) and R^(a5) to each other ispreferably an oxygen atom, a sulfur atom, a selenium atom, —NR^(a8)—,—CR^(a9)R^(a10)—, —SR^(a11)R^(a12)—, —CR^(a13)═CR^(a14)—, —N═CR^(a15)—,or —N═N—, and more preferably an oxygen atom or a sulfur atom. R^(a8) toR^(a15) each independently represent a hydrogen atom or a substituent.

R^(a1) which does not contribute to the formation of a ring ispreferably an alkyl group, an aryl group, a heteroaryl group, a—CO-alkyl group, a —CO-aryl group, or a —CO-heteroaryl group, which mayhave a substituent.

R^(a3) which does not contribute to the formation of a ring ispreferably an alkyl group, an aryl group, a heteroaryl group, or anon-aromatic heterocyclic group, which may have a substituent, and morepreferably an aryl group or a heteroaryl group.

R^(a2) and R^(a4) to R^(a7) which do not contribute to the formation ofa ring are each independently preferably a hydrogen atom, or an alkylgroup, an aryl group, or a heteroaryl group, which may have asubstituent.

In Formula (1), A represents a ring containing at least two carbonatoms. The two carbon atoms refer to a carbon atom in a carbonyl groupin Formula (1) and a carbon atom adjacent to the carbon atom in acarbonyl group, and both the carbon atoms are atoms constituting A.

Among these, the carbon number of A is preferably 3 to 30, morepreferably 3 to 20, and still more preferably 3 to 15. Theabove-described carbon number is a number containing two carbon atomsspecified in the formula.

A may have a hetero atom. For example, the hetero atom is preferably anitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, atellurium atom, a phosphorus atom, a silicon atom, and a boron atom, anda nitrogen atom, a sulfur atom, or an oxygen atom, and more preferablyan oxygen atom.

A may have a substituent, and the substituent is preferably a halogenatom.

The number of hetero atoms in A is preferably 0 to 10, more preferably 0to 5, and still more preferably 0 to 2. The number of hetero atoms isthe number excluding the number of oxygen atoms contained in a carbonylgroup constituting A specified in Formula (1) and the number of halogenatoms contained in A as a substituent.

A may or may not indicate aromaticity.

A may have a monocyclic structure or a condensed ring structure, but ispreferably a 5-membered ring, a 6-membered ring, or a fused ringcontaining at least any one of a 5-membered ring or a 6-membered ring.The number of rings forming the fused ring is preferably 1 to 4, andmore preferably 1 to 3.

Among these, it is preferable that the ring represented by A has a grouprepresented by Formula (A1) below. In addition, *¹ represents thebonding position with the carbon atom in the carbonyl group constitutingA specified in Formula (1), and *² represents the bonding position withthe other carbon atom different from the carbon atom in the carbonylgroup constituting A specified in Formula (1).

*¹-L-Y—Z—*²  (A1)

In Formula (A1), L represents a single bond or —NR^(L)—.

R^(L) represents a hydrogen atom or a substituent. Among these, R^(L) ispreferably an alkyl group, an aryl group, or a heteroaryl group, andmore preferably an alkyl group or an aryl group.

L is preferably a single bond.

Y represents —CR^(Y1)═CR^(Y2)—, —CS—NR^(Y3)—, —CS—, —NR^(Y4)—, or—N═CR^(Y5)—, and among these, —CR^(Y1)═CR^(Y2)— is preferable.

R^(Y1) to R^(Y5) each independently represent a hydrogen atom or asubstituent. Among these, R^(Y1) to R^(Y5) are each independentlypreferably an alkyl group, an aryl group, or a heteroaryl group, andmore preferably an alkyl group or an aryl group.

In a case where Y represents —CR^(Y1)═CR^(Y2)—, it is preferable thatR^(Y1) and R^(Y2) are linked to each other to form a ring, and morepreferable that R^(Y1) and R^(Y2) are linked to each other to form abenzene ring.

Z represents a single bond, —CO—, or —S—, and among these, —CO— ispreferable.

The above-described combination of L, Y, and Z is preferably acombination in which a ring formed by bonding -L-Y—Z— and two carbonatoms specified in Formula (1) to each other is a 5-membered ring or a6-membered ring. However, the 5-membered ring or the 6-membered ring maybe further condensed with a different ring (preferably, a benzene ring)to form a condensed ring structure as described above.

Among these, the group represented by Formula (A1) is more preferably agroup represented by Formula (A2) below.

In Formula (A2), A¹ and A² each independently represent a hydrogen atomor a substituent.

It is preferable that A¹ and A² are linked to each other to form a ring,and more preferable that A¹ and A² are linked to each other to form abenzene ring.

The benzene ring formed by A¹ and A² preferably further has asubstituent. Example of a substituent is preferably a halogen atom, andmore preferably a chlorine atom or a fluorine atom.

Also, the substituent included in the benzene ring formed by A¹ and A²may be further linked to each other to form a ring. For example, thesubstituent included in the benzene ring formed by A¹ and A² may befurther linked to each other to form a benzene ring.

Among these, the group represented by Formula (A1) is still morepreferably a group represented by Formula (A3) below.

In Formula (A3), A³ to A⁶ each independently represent a hydrogen atomor a substituent. Among these, A³ to A⁶ are each independentlypreferably a hydrogen atom or a halogen atom, and more preferably ahydrogen atom, a chlorine atom, or a fluorine atom.

A³ and A⁴ may be linked to each other to form a ring, A⁴ and A⁵ may belinked to each other to form a ring, and A⁵ and A⁶ may be linked to eachother to form a ring. The ring formed by linking A³ and A⁴, A⁴ and A⁵,and A⁵ and A⁶ to each other is preferably a benzene ring.

Among these, it is preferable that A⁴ and A⁵ are linked to each other toform a ring, and the ring formed by linking A⁴ and A⁵ to each other ispreferably a benzene ring. The ring formed by linking A⁴ and A⁵ to eachother may be further substituted with a substituent.

Such a ring is preferably a substance normally used as an acidic nucleuswith a merocyanine dye, and the specific examples thereof include thefollowings.

(a) 1,3-Dicarbonyl nucleus: for example, 1,3-indandione nucleus,1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6-dione, and the like.

(b) Pyrazolinone nucleus: for example, 1-phenyl-2-pyrazolin-5-one,3-methyl-1-phenyl-2-pyrazolin-5-one,1-(2-benzothiazolyl)-3-methyl-2-pyrazolin-5-one, and the like.

(c) Isoxazolinone nucleus: for example, 3-phenyl-2-isoxazolin-5-one,3-methyl-2-isoxazolin-5-one, and the like. (d) Oxindole nucleus: forexample, 1-alkyl-2,3-dihydro-2-oxindole, and the like.

(e) 2,4,6-Trioxohexahydropyrimidine nucleus: for example, barbituricacid, 2-thiobarbituric acid and derivatives thereof, or the like.Examples of the derivative include a 1-alkyl form such as 1-methyl and1-ethyl, a 1,3-dialkyl form such as 1,3-dimethyl, 1,3-diethyl, and1,3-dibutyl, a 1,3-diaryl form such as 1,3-diphenyl,1,3-di(p-chlorophenyl), 1,3-di(p-ethoxycarbonylphenyl), 1-alkyl-1-arylform such as 1-ethyl-3-phenyl, and a 1,3-diheteroaryl form such as1,3-di(2-pyridyl).

(f) 2-Thio-2,4-thiazolidinedione nucleus: for example, rhodanine andderivatives thereof. Examples of the derivatives include3-alkylrhodanine such as 3-methylrhodanine, 3-ethylrhodanine, and3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and3-heteroaryl rhodanine such as 3-(2-pyridyl)rhodanine.

(g) 2-Thio-2,4-oxazolidinedione(2-thio-2,4-(3H, 5H)-oxazoledionenucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione, and the like.

(h) Tianaphthenone nucleus: for example,3(2H)-thianaphthenone-1,1-dioxide, and the like.

(i) 2-Thio-2,5-thiazolidinedione nucleus: for example,3-ethyl-2-thio-2,5-thiazolidinedione, and the like.

(j) 2,4-Thiazolidinedione nucleus: for example, 2,4-thiazolidinedione,3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione, and thelike.

(k) Thiazolin-4-one nucleus: for example, 4-thiazolinone,2-ethyl-4-thiazolinone, and the like.

(l) 2,4-Imidazolidinedione (hydantoin) nucleus: for example,2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, and the like.

(m) 2-Thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: forexample, 2-thio-2,4-imidazolidinedione,3-ethyl-2-thio-2,4-imidazolidinedione, and the like.

(n) Imidazolin-5-one nucleus: for example,2-propylmercapto-2-imidazolin-5-one, and the like.

(o) 3,5-Pyrazolidinedione nucleus: for example,1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione,and the like.

(p) Benzothiophene-3(2H)-one nucleus: for example,benzothiophene-3(2H)-one, oxobenzothiophene-3(2H)-one,dioxobenzothiophene-3(2H)-one, and the like.

(q) Indanone nucleus: for example, 1-indanone, 3-phenyl-1-indanone,3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone,and the like.

(r) Benzofuran-3-(2H)-one nucleus: for example, benzofuran-3-(2H)-one,and the like.

(s) 2,2-Dihydrophenalene-1,3-dione nucleus, and the like.

The specific compound does not have any of a carboxy group, a salt of acarboxy group, a phosphoric acid group, a salt of a phosphoric acidgroup, a sulfonic acid group, or a salt of a sulfonic acid group fromthe viewpoint of avoiding deterioration in the vapor depositionsuitability.

In addition to the above-described groups and the salts thereof, fromthe viewpoint of avoiding deterioration in the vapor depositionsuitability, it is preferable that the specific compound does not haveany of a sulfuric monoester group, a monophosphate group, a phosphonicacid group, a phosphinic acid group, a boric acid group, and saltsthereof.

(Formula (2))

The specific compound is preferably a compound represented by Formula(2) below.

Formula (2) below corresponds to a case where m in Formula (1)represents 1 and R^(a4) and R^(a5) are linked to each other to form aring.

In Formula (2), R^(b1) to R^(b5) each independently represent a hydrogenatom or a substituent. The type of the substituent is not particularlylimited, but a group exemplified by a substituent W described below ismentioned.

Among these, R^(b1) is preferably an alkyl group, an aryl group, aheteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a—CO-heteroaryl group, which may have a substituent, more preferably analkyl group or an aryl group, and still more preferably an alkyl grouphaving 1 to 2 carbon atoms, a cyclohexyl group, or a phenyl group.

It is preferable that the phenyl group has an alkyl group (preferably, abranched alkyl group having 3 to 5 carbon atoms) as a substituent.

R^(b3) is preferably an alkyl group, an aryl group, a heteroaryl group,or a non-aromatic heterocyclic group (for example, a piperidine ringgroup), which may have a substituent, more preferably an aryl group or aheteroaryl group, which may have a substituent, and still morepreferably a phenyl group, a naphthyl group, a thienyl group, or acarbazole ring group, which may have a substituent.

It is preferable that the aryl group or the heteroaryl group representedby R^(b3) has, as a substituent, an alkyl group (more preferably, alinear or branched alkyl group having 1 to 5 carbon atoms), an alkoxygroup (more preferably, a methoxy group), or an aryl group (morepreferably, a phenyl group). It is also preferable that the alkyl group,the alkoxy group, and the aryl group as a substituent further have asubstituent, and the substituent thereof is preferably a halogen atom(more preferably a fluorine atom).

R^(b2), R^(b4), and R^(b5) are each independently preferably a hydrogenatom, or an alkyl group, an aryl group, or a heteroaryl group, which mayhave a substituent, and more preferably a hydrogen atom.

X¹ represents an oxygen atom, a sulfur atom, a selenium atom, —NR^(b6)—,—CR^(b7)R^(b8)—, —SiR^(b9)R^(b10)—, —CR^(b11)═CR^(b12)—, —N═CR^(b13)—,or —N═N—. R^(b6) to R^(b13) each independently represent a hydrogen atomor a substituent. R^(b6) to R^(b13) are each independently preferably ahydrogen atom, or an alkyl group, an aryl group (a phenyl group), aheteroaryl group, or a non-aromatic heterocyclic group (a piperidinering group), which may have a substituent.

Among these, X¹ is preferably an oxygen atom, a sulfur atom, —NR^(b6)—,or —CR^(b11)═CR^(b12)—, and more preferably an oxygen atom or a sulfuratom.

R^(b2) and R^(b3) may be linked to each other to form a ring.

In a case where X¹ represents —NR^(b6)—, —CR^(b7)R^(b8)—,—SiR^(b9)R^(b10)—, —CR^(b11)═CR^(b12)—, or —N═CR^(b13)—, any one ofR^(b6), R^(b7), R^(b8), R^(b9), R^(b10), R^(b11), R^(b12), or R^(b13)included in the group represented by X¹ and R^(b3) may be linked to eachother to form a ring.

R^(b4) and R^(b5) are not linked to each other to form a ring.

A in Formula (2) represents a ring containing at least two carbon atoms,and the preferred embodiment of A in Formula (2) is the same as thepreferred embodiment of A in Formula (1).

As described above, the compound represented by Formula (2) does nothave any of a carboxy group, a salt of a carboxy group, a phosphoricacid group, a salt of a phosphoric acid group, a sulfonic acid group, ora salt of a sulfonic acid group.

(Formula (3))

The specific compound is more preferably a compound represented byFormula (3) below.

In Formula (3), R^(c1) represents an alkyl group, an aryl group, aheteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a—CO-heteroaryl group, which may have a substituent. Among these, analkyl group or an aryl group is preferable, and an alkyl group having 1to 2 carbon atoms, a cyclohexyl group, or a phenyl group is morepreferable.

It is preferable that the phenyl group has an alkyl group (preferably, abranched alkyl group having 3 to 5 carbon atoms) as a substituent.

R^(c2) to R^(c7) each independently represent a hydrogen atom or asubstituent. The type of the substituent is not particularly limited,but a group exemplified by a substituent W described below is mentioned.

R^(c3) is preferably an alkyl group, an aryl group, a heteroaryl group,or a non-aromatic heterocyclic group (for example, a piperidine ringgroup), which may have a substituent, more preferably an aryl group or aheteroaryl group, which may have a substituent, and still morepreferably a phenyl group, a naphthyl group, a thienyl group, or acarbazole ring group, which may have a substituent.

It is preferable that the aryl group or the heteroaryl group representedby R^(c3) has, as a substituent, an alkyl group (more preferably, alinear or branched alkyl group having 1 to 5 carbon atoms), an alkoxygroup (more preferably, a methoxy group), or an aryl group (morepreferably, a phenyl group). It is also preferable that the alkyl group,the alkoxy group, and the aryl group as a substituent further have asubstituent, and the substituent thereof is preferably a halogen atom(more preferably a fluorine atom).

R^(c2) and R^(c3) may be linked to each other to form a ring, and R^(c5)and R^(c6) may be linked to each other to form a ring.

Among these, it is preferable that R^(c5) and R^(c6) are linked to eachother to form a benzene ring. That is, it is preferable to form a groupcorresponding to a group represented Formula (A3). In this case, thepreferred embodiment of the group corresponding to the group representedby Formula (A3) above is the same as the preferred embodiment of thegroup represented by Formula (A3). In this case, the carbon atom towhich R^(c5) specified in Formula (3) bonds corresponds to the carbonatom adjacent to *¹ in Formula (A3).

R^(c2), R^(c4), and R^(c7), are each independently preferably a hydrogenatom, or an alkyl group, an aryl group, or a heteroaryl group, and morepreferably a hydrogen atom.

X² represents an oxygen atom or a sulfur atom.

R^(c4) and R^(c7) are not linked to each other to form a ring.

As described above, the compound represented by Formula (3) does nothave any of a carboxy group, a salt of a carboxy group, a phosphoricacid group, a salt of a phosphoric acid group, a sulfonic acid group, ora salt of a sulfonic acid group.

(Substituent W)

The substituent W in the present specification will be described below.

Examples of the substituent W include a halogen atom, an alkyl group(including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkylgroup), an alkenyl group (including a cycloalkenyl group and abicycloalkenyl group), an alkynyl group, an aryl group, a heterocyclicgroup, a cyano group, a hydroxy group, a nitro group, an alkoxy group,an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group (including an anilino group),an ammonium group, an acylamino group, an aminocarbonylamino group, analkoxycarbonylamino group, an aryloxycarbonylamino group, asulfamoylamino group, an alkyl- or arylsulfonylamino group, a mercaptogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,a sulfamoyl group, an alkyl- or arylsulfinyl group, an alkyl- orarylsulfonyl group, an acyl group, an aryloxycarbonyl group, analkoxycarbonyl group, a carbamoyl group, an aryl- or heterocyclic azogroup, an imide group, a phosphino group, a phosphinyl group, aphosphinyloxy group, a phosphinylamino group, a phosphono group, a silylgroup, a hydrazino group, a ureido group, a boronic acid group(—B(OH)₂), and other well-known substituents.

Also, the substituent W may be further substituted with the substituentW. For example, an alkyl group may be substituted with a halogen atom.

The details of the substituent W are disclosed in paragraph [0023] ofJP2007-234651A.

However, as described above, the specific compound does not have any ofa carboxy group, a salt of a carboxy group, a phosphoric acid group, asalt of a phosphoric acid group, a sulfonic acid group, or a salt of asulfonic acid group from the viewpoint of avoiding deterioration in thevapor deposition suitability. Therefore, in the present specification,the substituent W included in the specific compound does not contain acarboxy group, a salt of a carboxy group, a phosphoric acid group, asalt of a phosphoric acid group, a sulfonic acid group, and a salt of asulfonic acid group.

The carbon number of an alkyl group included in the specific compound(the compound represented by Formulae (1) to (3)) is not particularlylimited, but preferably 1 to 10, more preferably 1 to 6, and still morepreferably 1 to 4. The alkyl group may be linear, branched, or cyclic.The alkyl group may be substituted with a substituent (for example, thesubstituent W).

Examples of the alkyl group include a methyl group, an ethyl group, ann-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, ann-hexyl group, and a cyclohexyl group.

The carbon number of an aryl group included in the specific compound(the compound represented by Formulae (1) to (3)) is not particularlylimited, but preferably 6 to 30, more preferably 6 to 18, and still morepreferably 6. The aryl group may have a monocyclic structure or acondensed ring structure (a fused ring structure) in which two or morerings are condensed. An aryl group may be substituted with a substituent(for example, the substituent W).

Examples of the aryl group include a phenyl group, a naphthyl group, ananthryl group, a pyrenyl group, a phenanthrenyl group, a methylphenylgroup, a dimethylphenyl group, a biphenyl group, and a fluorenyl group,and a phenyl group, a naphthyl group, or an anthryl group is preferable.

The carbon number of a heteroaryl group (a monovalent aromaticheterocyclic group) included in the specific compound (the compoundrepresented by Formulae (1) to (3)) is not particularly limited, butpreferably 3 to 30, and more preferably 3 to 18. The heteroaryl groupmay be substituted with a substituent (for example, the substituent W).

The heteroaryl group includes a hetero atom in addition to a carbon atomand a hydrogen atom. Examples of the hetero atom include a sulfur atom,an oxygen atom, a nitrogen atom, a selenium atom, a tellurium atom, aphosphorus atom, a silicon atom, and a boron atom, and a sulfur atom, anoxygen atom, or a nitrogen atom is preferable.

The number of hetero atoms contained in the heteroaryl group is notparticularly limited, but is usually about 1 to 10, preferably 1 to 4,and more preferably 1 to 2.

The number of ring members of the heteroaryl group is not particularlylimited, but is preferably 3 to 8, more preferably 5 to 7, and stillmore preferably 5 to 6. The heteroaryl group may have a monocyclicstructure or a condensed ring structure in which two or more rings arecondensed. In a case of the condensed ring structure, an aromatichydrocarbon ring having no hetero atom (for example, a benzene ring) maybe included.

Examples of the heteroaryl group include a pyridyl group, a quinolylgroup, an isoquinolyl group, an acridinyl group, a phenanthridinylgroup, a pteridinyl group, a pyrazinyl group, a quinoxalinyl group, apyrimidinyl group, a quinazolyl group, a pyridazinyl group, a cinnolinylgroup, a phthalazinyl group, a triazinyl group, an oxazolyl group, abenzoxazolyl group, a thiazolyl group, a benzothiazolyl group, animidazolyl group, a benzimidazolyl group, a pyrazolyl group, anindazolyl group, an isoxazolyl group, a benzisoxazolyl group, anisothiazolyl group, a benzisothiazolyl group, an oxadiazolyl group, athiadiazolyl group, a triazolyl group, a tetrazolyl group, a furylgroup, a benzofuryl group, a thienyl group, a benzothienyl group, adibenzofuryl group, a dibenzothienyl group, a pyrrolyl group, an indolylgroup, an imidazopyridinyl group, and a carbazolyl group.

Hereinafter, the compound represented by Formula (1) will beexemplified.

In a case where the compound was applied to Formula (1) (or Formula(2)), the structural formula shown below intends to include both the cisisomer and the trans isomer which are distinguished based on a groupcorresponding to the C═C double bond constituted by a carbon atom towhich R^(a7) (or R^(b5)) bonds and a carbon atom adjacent thereto.

In the following examples, “Me” represents a methyl group and “TMS”represents a trimethylsilyl group.

A molecular weight of the specific compound is not particularly limited,but is preferably 300 to 900. In a case where the molecular weight is900 or less, the vapor deposition temperature does not increase, and thedecomposition of the compound hardly occurs. In a case where themolecular weight is 300 or more, a glass transition point of a depositedfilm does not decrease, and a heat resistance of the photoelectricconversion element is improved.

The specific compound is particularly useful as a material of thephotoelectric conversion film used for the optical sensor, the imagingelement, or a photoelectric cell. In addition, the specific compoundusually functions as the p-type organic semiconductor in thephotoelectric conversion film in many cases. The specific compound canalso be used as a coloring material, a liquid crystal material, anorganic semiconductor material, a charge transport material, apharmaceutical material, and a fluorescent diagnostic material.

The specific compound is preferably a compound in which an ionizationpotential in a single film is −5.0 to −6.0 eV from the viewpoints ofstability in a case of using the compound as the p-type organicsemiconductor and matching of energy levels between the compound and then-type organic semiconductor.

In order to be applicable to the organic photoelectric conversion film209 that absorbs green light and performs photoelectric conversion, themaximum absorption wavelength of the specific compound is preferably inthe range of 450 to 600 nm, and is more preferably in the range of 480to 600 nm.

The maximum absorption wavelength is a value measured in a solutionstate (solvent: chloroform) by adjusting the absorption spectrum of thespecific compound to a concentration such that the light absorbance is0.5 to 1.

<n-Type Organic Semiconductor>

It is preferable that the photoelectric conversion film contains then-type organic semiconductor as a component other than the specificcompound.

The n-type organic semiconductor is an acceptor-property organicsemiconductor material (a compound), and refers to an organic compoundhaving a property of easily accepting an electron. More specifically,the n-type organic semiconductor refers to an organic compound having alarge electron affinity of two organic compounds used in contact witheach other.

Examples of the n-type organic semiconductor include a condensedaromatic carbocyclic compound (for example, fullerene, a naphthalenederivative, an anthracene derivative, a phenanthrene derivative, atetracene derivative, a pyrene derivative, a perylene derivative, and afluoranthene derivative); a 5 to 7 membered heterocyclic compound havingat least one of a nitrogen atom, an oxygen atom, or a sulfur atom (forexample, pyridine, pyrazine, pyrimidine, pyridazine, triazine,quinoline, quinoxaline, quinazoline, phthalazine, cinnoline,isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole,pyrazole, imidazole, and thiazole); a polyarylene compound; a fluorenecompound; a cyclopentadiene compound; a silyl compound; and a metalcomplex having a nitrogen-containing heterocyclic compound as theligands.

An organic dye may be used as the n-type organic semiconductor. Examplesof the organic dye include a cyanine dye, a styryl dye, a hemicyaninedye, a merocyanine dye (including zeromethine merocyanine (simplemerocyanine)), a rhodacyanine dye, an allopolar dye, an oxonol dye, ahemioxonol dye, a squarylium dye, a croconium dye, an azamethine dye, acoumarin dye, an arylidene dye, an anthraquinone dye, a triphenylmethanedye, an azo dye, an azomethine dye, a metallocene dye, a fluorenone dye,a flugide dye, a perylene dye, a phenazine dye, a phenothiazine dye, aquinone dye, a diphenylmethane dye, a polyene dye, an acridine dye, anacridinone dye, a diphenylamine dye, a quinophthalone dye, a phenoxazinedye, a phthaloperylene dye, a dioxane dye, a porphyrin dye, achlorophyll dye, a phthalocyanine dye, a subphthalocyanine dye, and ametal complex dye.

The molecular weight of the n-type organic semiconductor is preferably200 to 1200, and more preferably 200 to 900.

On the other hand, in a case of the form as shown in FIG. 2, it isdesirable that the n-type organic semiconductor is colorless, or has themaximum absorption wavelength and/or an absorption waveform close tothat of the specific compound, and a specific value of the maximumabsorption wavelength of the n-type organic semiconductor is desirably400 nm or less, or 500 to 600 nm.

It is preferable that the photoelectric conversion film has a bulkhetero structure formed in a state in which the specific compound andthe n-type organic semiconductor are mixed. The bulk hetero structurerefers to a layer in which the specific compound and the n-type organicsemiconductor are mixed and dispersed in the photoelectric conversionfilm. The photoelectric conversion film having the bulk hetero structurecan be formed by either a wet method or a dry method. The bulk heterostructure is described in detail in, for example, paragraphs [0013] to[0014] of JP2005-303266A.

The content of the specific compound to the total content of thespecific compound and the n-type organic semiconductor (=film thicknessin terms of single layer of specific compound/(film thickness in termsof single layer of specific compound+film thickness in terms of singlelayer of n-type organic semiconductor)×100) is preferably 20 to 80volume %, more preferably 30 to 70 volume %, and still more preferably40 to 60 volume % from the viewpoint of responsiveness of thephotoelectric conversion element.

It is preferable that the photoelectric conversion film is substantiallyformed of the specific compound and the n-type organic semiconductor.The term “substantially” means that the total content of the specificcompound and the n-type organic semiconductor to the total mass of thephotoelectric conversion film is 95 mass % or more.

The n-type organic semiconductor contained in the photoelectricconversion film may be used alone, or by a combination of two or moretypes.

The photoelectric conversion film may further contain a p-type organicsemiconductor in addition to the specific compound and the n-typeorganic semiconductor. Examples of the p-type organic semiconductorinclude examples shown below.

In a case where the specific compound is used as the p-type organicsemiconductor, the p-type organic semiconductor intends the p-typeorganic semiconductor other than the specific compound.

<p-Type Organic Semiconductor>

The p-type organic semiconductor is a donor-property organicsemiconductor material (a compound), and refers to an organic compoundhaving a property of easily donating an electron. More specifically, thep-type organic semiconductor refers to an organic compound having anionization potential of two organic compounds used in contact with eachother.

Examples of the p-type organic semiconductor (the p-type organicsemiconductor other than the specific compound) include a triarylaminecompound, a benzidine compound, a pyrazoline compound, a styrylaminecompound, a hydrazone compound, a carbazole compound, a polysilanecompound, a thiophene compound, a cyanine compound, an oxonol compound,a polyamine compound, an indole compound, a pyrrole compound, a pyrazolecompound, a polyarylene compound, a condensed aromatic carbocycliccompound, and metal complexes having a nitrogen-containing heterocycliccompound as ligands.

Examples of the p-type organic semiconductor include a compound havingan ionization potential smaller than that of the n-type organicsemiconductor. When this condition is satisfied, the organic dyeexemplified as the n-type organic semiconductor can be used.

The photoelectric conversion film containing the specific compound is anon-luminescent film, and has a feature different from an organic lightemitting diode (OLED). The non-luminescent film means a film having aluminescence quantum efficiency of 1% or less, and the luminescencequantum efficiency is preferably 0.5% or less, and more preferably 0.1%or less.

<Film Formation Method>

The photoelectric conversion film can be formed mostly by a dry filmformation method. Specific examples of the dry film formation methodinclude a physical vapor deposition method such as a vapor depositionmethod (in particular, a vacuum evaporation method), a sputteringmethod, an ion plating method, and molecular beam epitaxy (MBE), andchemical vapor deposition (CVD) such as plasma polymerization. Amongthese, the vacuum evaporation method is preferable. In a case where thephotoelectric conversion film is formed by the vacuum evaporationmethod, a producing condition such as a degree of vacuum and a vapordeposition temperature can be set according to the normal method.

The thickness of the photoelectric conversion film is preferably 10 to1000 nm, more preferably 50 to 800 nm, still more preferably 50 to 500nm, and particularly preferably 50 to 300 nm.

[Electrode]

The electrode (the upper electrode (the transparent conductive film) 15and the lower electrode (the conductive film) 11) is formed of aconductive material. Examples of the conductive material include metals,alloys, metal oxides, electrically conductive compounds, and mixturesthereof.

Since light is incident through the upper electrode 15, the upperelectrode 15 is preferably transparent to light to be detected. Examplesof the material forming the upper electrode 15 include conductive metaloxides such as tin oxide (ATO, FTO) doped with antimony, fluorine, orthe like, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO),and indium zinc oxide (IZO); metal thin films such as gold, silver,chromium, and nickel; mixtures or laminates of these metals and theconductive metal oxides; and organic conductive materials such aspolyaniline, polythiophene, and polypyrrole. Among these, conductivemetal oxides are preferable from the viewpoints of high conductivity,transparency, and the like.

In general, in a case where the conductive film is made to be thinnerthan a certain range, a resistance value is rapidly increased. However,in the solid-state imaging element into which the photoelectricconversion element according to the present embodiment is incorporated,the sheet resistance is preferably 100 to 10000Ω/□, and the degree offreedom of the range of the film thickness that can be thinned is large.In addition, as the thickness of the upper electrode (the transparentconductive film) 15 is thinner, the amount of light that the upperelectrode absorbs becomes smaller, and the light transmittance usuallyincreases. The increase in the light transmittance causes an increase inlight absorbance in the photoelectric conversion film and an increase inthe photoelectric conversion ability, which is preferable. Consideringthe suppression of leakage current, an increase in the resistance valueof the thin film, and an increase in transmittance accompanied by thethinning, the film thickness of the upper electrode 15 is preferably 5to 100 nm, and more preferably 5 to 20 nm.

There is a case where the lower electrode 11 has transparency or anopposite case where the lower electrode does not have transparency andreflects light, depending on the application. Examples of a materialconstituting the lower electrode 11 include conductive metal oxides suchas tin oxide (ATO, FTO) doped with antimony, fluorine, or the like, tinoxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zincoxide (IZO); metals such as gold, silver, chromium, nickel, titanium,tungsten, and aluminum, conductive compounds (for example, titaniumnitride (TiN)) such as oxides or nitrides of these metals; mixtures orlaminates of these metals and conductive metal oxides; and organicconductive materials such as polyaniline, polythiophene, andpolypyrrole.

The method of forming electrodes is not particularly limited, and can beappropriately selected in accordance with the electrode material.Specific examples thereof include a wet method such as a printing methodand a coating method; a physical method such as a vacuum evaporationmethod, a sputtering method, and an ion plating method; and a chemicalmethod such as a CVD method and a plasma CVD method.

In a case where the material of the electrode is ITO, examples thereofinclude an electron beam method, a sputtering method, a resistancethermal vapor deposition method, a chemical reaction method (such as asol-gel method), and a coating method with a dispersion of indium tinoxide.

[Charge Blocking Film: Electron Blocking Film and Positive Hole BlockingFilm]

It is also preferable that the photoelectric conversion element of theembodiment of the invention has one or more interlayers between theconductive film and the transparent conductive film, in addition to thephotoelectric conversion film. Example of the interlayer includes thecharge blocking film. In the case where the photoelectric conversionelement has this film, the characteristics (such as photoelectricconversion efficiency and responsiveness) of the photoelectricconversion element to be obtained become superior. Examples of thecharge blocking film include the electron blocking film and the positivehole blocking film. Hereinafter, the films will be described in detail.

<Electron Blocking Film>

The electron blocking film includes an electron donating compound.Specific examples of a low molecular material include aromatic diaminecompounds such as N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine(TPD) and 4,4′-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD);porphyrin compounds such as porphyrin, copper tetraphenylporphyrin,phthalocyanine, copper phthalocyanine, and titanium phthalocyanineoxide; and oxazole, oxadiazole, triazole, imidazole, imidazolone, astilbene derivative, a pyrazoline derivative, tetrahydroimidazole,polyarylalkane, butadiene,4,4′,4″-tris(N-(3-methylphenyl)-N-phenylamino) triphenylamine(m-MTDATA), a triazole derivative, an oxadiazole derivative, animidazole derivative, a polyarylalkane derivative, a pyrazolinederivative, a pyrazolone derivative, a phenylenediamine derivative, anarylamine derivative, an amino-substituted chalcone derivative, anoxazole derivative, a styrylanthracene derivative, a fluorenonederivative, a hydrazone derivative, and a silazane derivative. Specificexamples of a polymer material include a polymer such asphenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole,picoline, thiophene, acetylene, and diacetylene, and a derivativethereof. In addition, compounds described in paragraphs [0049] to [0063]of JP5597450B, compounds described in paragraphs [0119] to [0158] ofJP2011-225544A, and compounds described in paragraphs [0086] to [0090]of JP2012-094660A are exemplified.

The electron blocking film may be configured by a plurality of films.

The electron blocking film may be formed of an inorganic material. Ingeneral, an inorganic material has a dielectric constant larger thanthat of an organic material. Therefore, in a case where the inorganicmaterial is used in the electron blocking film, a large voltage isapplied to the photoelectric conversion film. Therefore, thephotoelectric conversion efficiency increases. Examples of the inorganicmaterial that can be used in the electron blocking film include calciumoxide, chromium oxide, copper chromium oxide, manganese oxide, cobaltoxide, nickel oxide, copper oxide, copper gallium oxide, copperstrontium oxide, niobium oxide, molybdenum oxide, copper indium oxide,silver indium oxide, and iridium oxide.

(Positive Hole Blocking Film)

The positive hole blocking film includes an electron accepting compound.

Examples of the electron accepting compound include an oxadiazolederivative such as1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)phenylene (OXD-7); ananthraquinodimethane derivative; a diphenylquinone derivative;bathocuproine, bathophenanthroline, and derivatives thereof; a triazolecompound; a tris(8-hydroxyquinolinato)aluminum complex; abis(4-methyl-8-quinolinato)aluminum complex; a distyrylarylenederivative; and a silole compound. In addition, compounds described inparagraphs [0056] to [0057] of JP2006-100767A are exemplified.

The method of producing the charge blocking film is not particularlylimited, a dry film formation method and a wet film formation method areexemplified. Examples of the dry film formation method include a vapordeposition method and a sputtering method. The vapor deposition methodmay be any of physical vapor deposition (PVD) method and chemical vapordeposition (CVD) method, and physical vapor deposition method such asvacuum evaporation method is preferable. Examples of the wet filmformation method include an inkjet method, a spray method, a nozzleprinting method, a spin coating method, a dip coating method, a castingmethod, a die coating method, a roll coating method, a bar coatingmethod, and a gravure coating method, and an inkjet method is preferablefrom the viewpoint of high precision patterning.

Each thickness of the charge blocking films (the electron blocking filmand the positive hole blocking film) is preferably 3 to 200 nm, morepreferably 5 to 100 nm, and still more preferably 5 to 30 nm.

[Substrate]

The photoelectric conversion element may further include a substrate.The type of substrate to be used is not particularly limited, and asemiconductor substrate, a glass substrate, and a plastic substrate areexemplified.

The position of the substrate is not particularly limited, but ingeneral, the conductive film, the photoelectric conversion film, and thetransparent conductive film are laminated on the substrate in thisorder.

[Sealing Layer]

The photoelectric conversion element may further include a sealinglayer. The performance of the photoelectric conversion material maydeteriorate noticeably due to the presence of deterioration factors suchas water molecules. The deterioration can be prevented by sealing andcoating the entirety of the photoelectric conversion film with thesealing layer such as diamond-like carbon (DLC) or ceramics such asmetal oxide, or metal nitride, and metal nitride oxide which are denseand into which water molecules do not permeate.

The material of the sealing layer may be selected and the sealing layermay be produced according to the description in paragraphs [0210] to[0215] of JP2011-082508A.

[Optical Sensor]

Examples of the application of the photoelectric conversion elementinclude the photoelectric cell and the optical sensor, but thephotoelectric conversion element of the embodiment of the invention ispreferably used as the optical sensor. The photoelectric conversionelement may be used alone as the optical sensor. Alternately, thephotoelectric conversion element may be used as a line sensor in whichthe photoelectric conversion elements are linearly arranged or as atwo-dimensional sensor in which the photoelectric conversion elementsare planarly arranged. In the line sensor of the embodiment of theinvention, the photoelectric conversion element of the inventionfunctions as the imaging element by converting optical image informationinto an electric signal using an optical system such as a scanner, and adriving unit. In the two-dimensional sensor, the photoelectricconversion element of the invention functions as the imaging element byconverting the optical image information into the electric signal byimaging the optical image information on the sensor using the opticalsystem such as an imaging module.

[Imaging Element]

Next, a configuration example of an imaging element comprising thephotoelectric conversion element 10 a will be described.

In the configuration example which will be described below, the samereference numerals or the corresponding reference numerals are attachedto members or the like having the same configuration or action as thosewhich have already been described, to simplify or omit the description.

The imaging element is an element that converts optical information ofan image into the electric signal, and is an element in which aplurality of photoelectric conversion elements are arranged on a matrixin the same planar form, optical signals are converted into electricsignals in each photoelectric conversion element (a pixel), and theelectric signals can be sequentially output to the outside of theimaging elements for each pixel. For this reason, one pixel is formed ofone photoelectric conversion element and one or more transistors.

FIG. 3 is a schematic cross-sectional view showing a schematicconfiguration of an imaging element for describing an embodiment of theinvention. This imaging element is mounted on an imaging device such asa digital camera and a digital video camera, an electronic endoscope,and imaging modules such as a cellular phone.

The imaging element has a plurality of photoelectric conversion elementshaving configurations shown in FIG. 1A and a circuit substrate in whichthe readout circuit reading out signals corresponding to chargesgenerated in the photoelectric conversion film of each photoelectricconversion element is formed. The imaging element has a configuration inwhich the plurality of photoelectric conversion elements areone-dimensionally or two-dimensionally arranged on the same surfaceabove the circuit substrate.

An imaging element 100 shown in FIG. 3 comprises a substrate 101, aninsulating layer 102, connection electrodes 103, pixel electrodes (lowerelectrodes) 104, connection units 105, connection units 106, aphotoelectric conversion film 107, a counter electrode (upper electrode)108, a buffer layer 109, a sealing layer 110, a color filter (CF) 111,partition walls 112, a light shielding layer 113, a protective layer114, a counter electrode voltage supply unit 115, and readout circuits116.

The pixel electrode 104 has the same function as the lower electrode 11of the photoelectric conversion element 10 a shown in FIG. 1A. Thecounter electrode 108 has the same function as the upper electrode 15 ofthe photoelectric conversion element 10 a shown in FIG. 1A. Thephotoelectric conversion film 107 has the same configuration as a layerprovided between the lower electrode 11 and the upper electrode 15 ofthe photoelectric conversion element 10 a shown in FIG. 1A.

The substrate 101 is a semiconductor substrate such as the glasssubstrate, or Si. The insulating layer 102 is formed on the substrate101. A plurality of pixel electrodes 104 and a plurality of connectionelectrodes 103 are formed on the surface of the insulating layer 102.

The photoelectric conversion film 107 is a layer common to all thephotoelectric conversion elements provided so as to cover the pluralityof pixel electrodes 104.

The counter electrode 108 is one electrode common to all thephotoelectric conversion elements provided on the photoelectricconversion film 107. The counter electrode 108 is formed on theconnection electrodes 103 arranged on an outer side than thephotoelectric conversion film 107, and is electrically connected to theconnection electrodes 103.

The connection units 106 are buried in the insulating layer 102, and areplugs for electrically connecting the connection electrodes 103 to thecounter electrode voltage supply unit 115. The counter electrode voltagesupply unit 115 is formed in the substrate 101, and applies apredetermined voltage to the counter electrode 108 via the connectionunits 106 and the connection electrodes 103. In a case where a voltageto be applied to the counter electrode 108 is higher than a power supplyvoltage of the imaging element, the power supply voltage is boosted by aboosting circuit such as a charge pump to supply the predeterminedvoltage.

The readout circuits 116 are provided on the substrate 101 correspondingto each of the plurality of pixel electrodes 104, and read out signalscorresponding to charges trapped by the corresponding pixel electrodes104. The readout circuits 116 are configured, for example, of CCD andCMOS circuits, or a thin film transistor (TFT) circuit, and are shieldedby the light shielding layer not shown in the drawing which is disposedin the insulating layer 102. The readout circuits 116 are electricallyconnected to the corresponding the pixel electrodes 104 via theconnection units 105.

The buffer layer 109 is formed on the counter electrode 108 so as tocover the counter electrode 108. The sealing layer 110 is formed on thebuffer layer 109 so as to cover the buffer layer 109. The color filters111 are formed on the sealing layer 110 at positions corresponding toeach of the pixel electrodes 104. The partition walls 112 are providedbetween the color filters 111, and are used for improving the lighttransmittance of the color filters 111.

The light shielding layer 113 is formed on the sealing layer 110 in aregion other than the region where the color filters 111 and thepartition walls 112 are provided, and prevents light from being incidentto the photoelectric conversion film 107 formed outside an effectivepixel region. The protective layer 114 is formed on the color filters111, the partition walls 112, and the light shielding layer 113, andprotects the entirety of the imaging element 100.

In the imaging element 100 configured as described above, light whichhas entered is incident on the photoelectric conversion film 107, andcharges are generated in the photoelectric conversion film. The positiveholes among the generated charges are trapped by the pixel electrodes104, and voltage signals corresponding to the amount are output to theoutside of the imaging element 100 using the readout circuits 116.

A method of producing the imaging element 100 is as follows. Theconnection units 105 and 106, the plurality of connection electrodes103, the plurality of pixel electrodes 104, and the insulating layer 102are formed on the circuit substrate in which the counter electrodevoltage supply unit 115 and the readout circuits 116 are formed. Theplurality of pixel electrodes 104 are disposed, for example, on thesurface of the insulating layer 102 in a square lattice shape.

Next, the photoelectric conversion film 107 is formed on the pluralityof pixel electrodes 104, for example, by the vacuum evaporation method.Next, the counter electrode 108 is formed on the photoelectricconversion film 107 under vacuum, for example, by the sputtering method.Next, the buffer layer 109 and the sealing layer 110 are sequentiallyformed on the counter electrode 108, for example, by the vacuumevaporation method. Next, after the color filters 111, the partitionwalls 112, and the light shielding layer 113 are formed, the protectivelayer 114 is formed, and the production of the imaging element 100 iscompleted.

EXAMPLES

Examples will be shown below, but the invention is not limited thereto.

Synthesis of Compound (D-1)

A compound (D-1) was synthesized according to the following scheme. Inthe following, “Et” represents an ethyl group and “Ac” represents anacetyl group.

A compound (A-1) was synthesized from 2-bromo-5-furaldehyde according tothe method disclosed in Chem. Eur. J. 2009, 15, 1096-1106.

The compound (A-1) (3.10 g, 10.9 mmol) was dissolved inN,N-dimethylformamide (DMF) (60 mL), iodoethane (5.08 g, 32.6 mmol) andpotassium carbonate (6.23 g, 45.1 mmol) were added thereto, and theobtained mixed liquid was stirred with heating at 90° C. for 2 hours.After the mixed liquid was allowed to cool, the mixed liquid was addedto water (300 mL) to precipitate a solid. The precipitated solid wasfiltered and washed with water. The obtained solid was vacuum dried toobtain a compound (A-2) (2.97 g, yield 96%).

The compound (A-2) (1.85 g, 5.90 mmol) was dissolved in ethanol (54 mL),a 1M aqueous sodium hydroxide solution (18 mL) was added thereto, andthe obtained mixed liquid was reacted under heating reflux for 5 hours.After the mixed liquid was cooled to room temperature, a 1M aqueoushydrochloric acid solution was added until pH of the mixed liquidreached 1, and the solid was precipitated. The precipitated solid wasfiltered and washed with water. The obtained solid was vacuum dried toobtain a compound (A-3) (1.60 g, yield 95%).

The mixed liquid obtained by adding trifluoroacetic acid (TFA) (15 mL)to the compound (A-3) (4.40 g, 17.2 mmol) was reacted at roomtemperature for 15 minutes. Thereafter, ethyl orthoformate (5.0 mL) wasadded to the mixed liquid, and the mixed liquid was further reacted atroom temperature for 15 minutes. The mixed liquid was added to asaturated aqueous sodium hydrogen carbonate solution (300 mL) andstirred for 30 minutes to precipitate a solid. The precipitated solidwas filtered and washed with water. The obtained solid was vacuum driedto obtain a compound (A-4) (2.72 g, yield 66%).

A mixed liquid obtained by adding the compound (A-4) (1.30 g, 5.43 mmol)and a compound (A-5) (1.12 g, 5.70 mmol) to an acetic acid (40 mL) wasreacted at 70° C. for 4 hours. After the mixed liquid was cooled to roomtemperature, methanol (80 mL) was added to the mixed liquid and stirredfor 30 minutes to precipitate a solid. The precipitated solid wasfiltered and washed with methanol to obtain a crude product.

The obtained crude product was recrystallized from chlorobenzene (100mL), and the solid obtained by recrystallization was washed withmethanol to obtain the compound (D-1) (1.48 g, yield 65%). The obtainedcompound (D-1) was identified by a ¹H nuclear magnetic resonance (NMR)and a mass spectrometry (MS).

¹H NMR spectrum (400 MHz, CDCl₃) is shown in FIG. 4.

MS(ESI⁺) m/z: 418.1 ([M+H]⁺)

With reference to the synthesis method of the compound (D-1), compounds(D-2) to (D-24) were synthesized. The structures of the obtainedcompounds (D-1) to (D-24) and the comparative compounds (R-1) to (R-3)are specifically shown below.

¹H NMR spectra (400 MHz, CDCl₃) of the compounds (D-3), (D-4), and (D-6)are shown in FIGS. 5 to 7.

In a case where the obtained compounds (D-1) to (D-24) were applied toFormula (1) or (2), the structural formula shown below intends toinclude both the cis isomer and the trans isomer which are distinguishedbased on a group corresponding to the C═C double bond constituted by acarbon atom to which R^(a7) or R^(b5) bonds and a carbon atom adjacentthereto.

<Production of Reference Photoelectric Conversion Element>

The photoelectric conversion element of the form of FIG. 1A was producedusing the obtained compound. In other words, the photoelectricconversion element to be evaluated in the present example is formed ofthe lower electrode 11, the electron blocking film 16A, thephotoelectric conversion film 12, and the upper electrode 15.

Specifically, an amorphous ITO was formed into a film on the glasssubstrate by the sputtering method to form the lower electrode 11 (athickness: 30 nm). Furthermore, the compound (EB-1) was formed into afilm on the lower electrode 11 by the vacuum evaporation method to formthe electron blocking film 16A (a thickness: 30 nm).

Furthermore, the compound (R-1) as the p-type organic semiconductor andthe fullerene (C₆₀) as the n-type organic semiconductor were subjectedto co-vapor deposition by the vacuum evaporation method so as to berespectively 100 nm in terms of single layer on the electron blockingfilm 16A to form a film in a state where the temperature of thesubstrate was controlled to 25° C., and the photoelectric conversionfilm 12 having the bulk hetero structure of 200 nm was formed.Furthermore, amorphous ITO was formed into a film on the photoelectricconversion film 12 by a sputtering method to form the upper electrode 15(the transparent conductive film) (the thickness: 10 nm). After the SiOfilm was formed as the sealing layer on the upper electrode 15 by avacuum evaporation method, an aluminum oxide (Al₂O₃) layer was formedthereon by an atomic layer chemical vapor deposition (ALCVD) method toproduce a photoelectric conversion element.

The obtained photoelectric conversion element was to be an element (A).

<Production of Evaluation Photoelectric Conversion Element>

Example Using Compound (R-1)

The photoelectric conversion element was produced according to the samemethod as that of the element (A) except that the film thickness of thephotoelectric conversion film.

Specifically, the compound (R-1) and the fullerene (C₆₀) were subjectedto co-vapor deposition by the vacuum evaporation method so as to berespectively 50 nm in terms of single layer on the electron blockingfilm 16A to form a film in a state where the temperature of thesubstrate was controlled to 25° C., and the photoelectric conversionfilm 12 having the bulk hetero structure of 100 nm was formed.

The obtained photoelectric conversion element was to be an element(B_(R-1)).

Examples Using Compounds (D-1) to (D-24) or (R-2) to (R-3)

The photoelectric conversion element was produced according to the samemethod as that of the element (B_(R-1)) except that the compound (R-1)was changed to compounds (D-1) to (D-24) or (R-2) to (R-3).

The photoelectric conversion elements obtained using the compounds (D-1)to (D-24) were referred to as elements (B_(D-1)) to (B_(D-24)),respectively.

On the other hand, in a case where the compounds (R-2) to (R-3) wereused, the compounds (R-2) to (R-3) could not be vapor-deposited.

<Evaluation of Photoelectric Conversion Efficiency>

A voltage was applied to each of the produced elements (A), (B_(D-1)) to(B_(D-24)), and (B_(R-1)) so as to obtain an electric field strength of2.0×10⁵ V/cm, and the maximum value of photoelectric conversionefficiency was measured.

The maximum value of the photoelectric conversion efficiency of theelement (A) was set as 1 to evaluate the maximum value of thephotoelectric conversion efficiency of each of other elements withrespect to that of the element (A) using a relative value. Regarding therelative value of the photoelectric conversion efficiency of theelement, a case of 1.1 or more was set as “A”, a case of 1.0 or more andless than 1.1 was set as “B”, and a case of less than 1.0 was set as“C”.

The results are shown in Table 1. For practical use, “A” or “B” ispreferable, and “A” is more preferable.

The evaluation results of the elements produced using each compound areshown in Table 1.

In Table 1, the column “X¹” indicates whether the group represented byX¹ is an oxygen atom or a sulfur atom in a case where the compounds(D-1) to (D-24) were applied to Formula (2). A case where the grouprepresented by X¹ is an oxygen atom or a sulfur atom is “presence”, anda case where the group is not an oxygen atom or a sulfur atom is“absence”.

In Table 1, the column “R^(b1)” indicates whether the group representedby R^(b1) is an alkyl group or an aryl group in a case where thecompounds (D-1) to (D-24) were applied to Formula (2). A case where thegroup represented by R^(b1) is an alkyl group or an aryl group is“presence”, and a case where the group is not an alkyl group or an arylgroup is “absence”.

In Table 1, the column “Formula (A2)” indicates the presence or absenceof the group represented by Formula (A2) in a case where the compounds(D-1) to (D-24) were applied to Formula (2).

In Table 1, the column “R^(c3)” indicates whether the group representedby R^(c3) is an aryl group or a heteroaryl group in a case where thecompounds (D-1) to (D-24) were applied to Formula (3). A case where thegroup represented by R^(c3) is an aryl group or a heteroaryl group is“presence”, and a case where the group is not an aryl group or aheteroaryl group is “absence”. The compounds which were not applied toFormula (3) was set as “-”.

TABLE 1 Photoelectric Formula conversion Compound X¹ R^(b1) (A2) R^(c3)Element efficiency Example 1 D-1 Presence Presence Presence PresenceB_(D-1) A Example 2 D-2 Presence Presence Presence Presence B_(D-2) AExample 3 D-3 Presence Presence Presence Presence B_(D-3) A Example 4D-4 Presence Presence Presence Presence B_(D-4) A Example 5 D-5 PresencePresence Presence Presence B_(D-5) A Example 6 D-6 Presence PresenceAbsence — B_(D-6) B Example 7 D-7 Presence Presence Absence — B_(D-7) BExample 8 D-8 Presence Presence Absence — B_(D-8) B Example 9 D-9Presence Presence Presence Presence B_(D-9) A Example 10 D-10 PresencePresence Presence Presence B_(D-10) A Example 11 D-11 Presence PresencePresence Presence B_(D-11) A Example 12 D-12 Presence Presence PresencePresence B_(D-12) A Example 13 D-13 Presence Presence Presence PresenceB_(D-13) A Example 14 D-14 Presence Presence Presence Absence B_(D-14) BExample 15 D-15 Presence Presence Presence Absence B_(D-15) B Example 16D-16 Presence Presence Presence Presence B_(D-16) A Example 17 D-17Presence Presence Presence Presence B_(D-17) A Example 18 D-18 PresencePresence Presence Presence B_(D-18) A Example 19 D-19 Presence PresencePresence Presence B_(D-19) A Example 20 D-20 Absence Presence Presence —B_(D-20) B Example 21 D-21 Presence Absence Presence — B_(D-21) BExample 22 D-22 Absence Absence Absence — B_(D-22) B Example 23 D-23Presence Presence Presence Absence B_(D-23) B Example 24 D-24 PresencePresence Presence Presence B_(D-24) A Comparative R-1 — — — — B_(R-1) CExample 1 Comparative R-2 — — — — Not vapor-deposited Example 2Comparative R-3 — — — — Not vapor-deposited Example 3

As shown in Table 1 above, it was confirmed that the photoelectricconversion element of the embodiment the invention has a photoelectricconversion film excellent in vapor deposition suitability, and exhibitsexcellent photoelectric conversion efficiency even when thephotoelectric conversion film is a thin film.

In a case where X¹ in Formula (2) is an oxygen atom or a sulfur atom, itwas confirmed that the photoelectric conversion element tends to exhibitmore excellent photoelectric conversion efficiency in a case of the thinfilm (comparison of Example 20 with other examples).

In a case where R^(b1) in Formula (2) is an alkyl group or an arylgroup, it was confirmed that the photoelectric conversion element tendsto exhibit more excellent photoelectric conversion efficiency in a caseof a thin film (comparison of Example 21 with Example 1).

In a case where the compound represented by Formula (2) has a grouprepresented by Formula (A2), it was confirmed that the photoelectricconversion element tens to exhibit more excellent photoelectricconversion efficiency in a case of a thin film (comparison of Examples 6to 8 with other examples).

In a case where R^(c3) in Formula (3) is an aryl group or a heteroarylgroup, it was confirmed that the photoelectric conversion element tendsto exhibit more excellent photoelectric conversion efficiency in a caseof a thin film (comparison of Examples 14, 15, and 23 with otherexamples).

<Production of Imaging Element>

The same imaging element as shown in FIG. 3 was produced using thecompounds (D-1) to (D-24) and (R-1).

That is, 30 nm of an amorphous TiN was formed into a film on a CMOSsubstrate by a sputtering method, and was used as the lower electrodethrough patterning such that each pixel was present on the photodiode(PD) on the CMOS substrate through photolithography, and then theimaging element was produced similarly to the element (A) and theelements (B_(D-1)) to (B_(D-24)) or (BRA) after the film formation ofthe electron blocking material. In the obtained imaging element, thephotoelectric conversion efficiency in a case where the photoelectricconversion film was a thin film was similarly evaluated, and the sameresults as in Table 1 were obtained. From this, it was found that thephotoelectric conversion element of the embodiment of the invention alsoexhibits excellent performance in the imaging element.

EXPLANATION OF REFERENCES

-   -   10 a, 10 b: photoelectric conversion element    -   11: conductive film (lower electrode)    -   12: photoelectric conversion film    -   15: transparent conductive film (upper electrode)    -   16A: electron blocking film    -   16B: positive hole blocking film    -   100: pixel separation type imaging element    -   101: substrate    -   102: insulating layer    -   103: connection electrode    -   104: pixel electrode (lower electrode)    -   105: connection unit    -   106: connection unit    -   107: photoelectric conversion film    -   108: counter electrode (upper electrode)    -   109: buffer layer    -   110: sealing layer    -   111: color filter (CF)    -   112: partition wall    -   113: light shielding layer    -   114: protective layer    -   115: counter electrode voltage supply unit    -   116: readout circuit    -   200: photoelectric conversion element (hybrid type photoelectric        conversion element)    -   201: inorganic photoelectric conversion film    -   202: n-type well    -   203: p-type well    -   204: n-type well    -   205: p-type silicon substrate    -   207: insulating layer    -   208: pixel electrode    -   209: organic photoelectric conversion film    -   210: common electrode    -   211: protective film    -   212: electron blocking film

What is claimed is:
 1. A photoelectric conversion element comprising: a conductive film; a photoelectric conversion film; and a transparent conductive film, in this order, wherein the photoelectric conversion film contains a compound represented by Formula (1),

in Formula (1), m represents an integer of 0 or more, R^(a1) to R^(a7) each independently represent a hydrogen atom or a substituent, R^(a1) to R^(a7) may be linked to each other to form a ring, in a case where a plurality of R^(a2)s are present, the plurality of R^(a2)s may be linked to each other to form a ring, in a case where a plurality of R^(a4)s are present, the plurality of R^(a4)s may be linked to each other to form a ring, and A represents a ring containing at least two carbon atoms, provided that, the compound represented by Formula (1) does not have any of a carboxy group, a salt of a carboxy group, a phosphoric acid group, a salt of a phosphoric acid group, a sulfonic acid group, or a salt of a sulfonic acid group.
 2. The photoelectric conversion element according to claim 1, wherein the compound represented by Formula (1) is a compound represented by Formula (2),

in Formula (2), R^(b1) to R^(b5) each independently represent a hydrogen atom or a substituent, X¹ represents an oxygen atom, a sulfur atom, a selenium atom, —NR^(b6)—, —CR^(b7)R^(b8)—, —SiR^(b9)R^(b10)—, —CR^(b11)═CR^(b12)—, —N═CR^(b13)—, or —N═N—, R^(b6) to R^(b13) each independently represent a hydrogen atom or a substituent, R^(b2) and R^(b3) may be linked to each other to form a ring, in a case where X¹ represents —NR^(b6)—, —CR^(b7)R^(b8)—, —SiR^(b9)R^(b10)—, —CR^(b11)═CR^(b12)—, or —N═CR^(b13)—, any one of R^(b6), R^(b7), R^(b8), R^(b9), R^(b10), R^(b11), R^(b12), or R^(b13) included in the group represented by X¹ and R^(b3) may be linked to each other to form a ring, and A represents a ring containing at least two carbon atoms, provided that, the compound represented by Formula (2) does not have any of a carboxy group, a salt of a carboxy group, a phosphoric acid group, a salt of a phosphoric acid group, a sulfonic acid group, or a salt of a sulfonic acid group.
 3. The photoelectric conversion element according to claim 2, wherein R^(b1) represents an alkyl group, an aryl group, a heteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a —CO-heteroaryl group, which may have a substituent.
 4. The photoelectric conversion element according to claim 2, wherein X¹ represents an oxygen atom, a sulfur atom, —NR^(b6)—, or —CR^(b11)═CR^(b12)—.
 5. The photoelectric conversion element according to claim 2, wherein X¹ represents an oxygen atom or a sulfur atom.
 6. The photoelectric conversion element according to claim 1, wherein the compound represented by Formula (1) is a compound represented by Formula (3),

in Formula (3), R^(c1) represents an alkyl group, an aryl group, a heteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a —CO-heteroaryl group, which may have a substituent, R^(c2) to R^(c7) each independently represent a hydrogen atom or a substituent, X² represents an oxygen atom or a sulfur atom, R^(c2) and R^(c3) may be linked to each other to form a ring, and R^(c5) and R^(c6) may be linked to each other to form a ring, provided that, the compound represented by Formula (3) does not have any of a carboxy group, a salt of a carboxy group, a phosphoric acid group, a salt of a phosphoric acid group, a sulfonic acid group, or a salt of a sulfonic acid group.
 7. The photoelectric conversion element according to claim 6, wherein R^(c3) represents an aryl group or a heteroaryl group, which may have a substituent.
 8. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion film further contains an n-type organic semiconductor and has a bulk hetero structure formed in a state where the compound represented by Formula (1) and the n-type organic semiconductor are mixed.
 9. The photoelectric conversion element according to claim 1, further comprising one or more interlayers between the conductive film and the transparent conductive film, in addition to the photoelectric conversion film.
 10. An optical sensor comprising the photoelectric conversion element according to claim
 1. 11. An imaging element comprising the photoelectric conversion element according to claim
 1. 12. A compound represented by Formula (3),

in Formula (3), R^(c1) represents an alkyl group, an aryl group, a heteroaryl group, a —CO-alkyl group, a —CO-aryl group, or a —CO-heteroaryl group, which may have a substituent, R^(c2) to R^(c7) each independently represent a hydrogen atom or a substituent, X² represents an oxygen atom or a sulfur atom, R^(c2) and R^(c3) may be linked to each other to form a ring, and R^(c5) and R^(c6) may be linked to each other to form a ring, provided that, the compound represented by Formula (3) does not have any of a carboxy group, a salt of a carboxy group, a phosphoric acid group, a salt of a phosphoric acid group, a sulfonic acid group, or a salt of a sulfonic acid group.
 13. The photoelectric conversion element according to claim 3, wherein X¹ represents an oxygen atom, a sulfur atom, —NR^(b6)— or —CR^(b11)═CR^(b12)—.
 14. The photoelectric conversion element according to claim 3, wherein X¹ represents an oxygen atom or a sulfur atom.
 15. The photoelectric conversion element according to claim 2, wherein the photoelectric conversion film further contains an n-type organic semiconductor and has a bulk hetero structure formed in a state where the compound represented by Formula (1) and the n-type organic semiconductor are mixed.
 16. The photoelectric conversion element according to claim 2, further comprising one or more interlayers between the conductive film and the transparent conductive film, in addition to the photoelectric conversion film.
 17. An optical sensor comprising the photoelectric conversion element according to claim
 2. 18. An imaging element comprising the photoelectric conversion element according to claim
 2. 19. The photoelectric conversion element according to claim 4, wherein X¹ represents an oxygen atom or a sulfur atom.
 20. The photoelectric conversion element according to claim 3, wherein the photoelectric conversion film further contains an n-type organic semiconductor and has a bulk hetero structure formed in a state where the compound represented by Formula (1) and the n-type organic semiconductor are mixed. 